Monocyte Recruitment Versus Macrophage Proliferation in Atherosclerosis

Therapeutic potential of paeoniflorin in atherosclerosis: A cellular action and mechanism-based perspective

Epidemiological studies have shown that the incidence, prevalence and mortality of atherosclerotic cardiovascular disease (ASCVD) are increasing globally. Atherosclerosis is characterized as a chronic inflammatory disease which involves inflammation and immune dysfunction. P. lactiflora Pall. is a plant origin traditional medicine that has been widely used for the treatment of various diseases for more than a millennium in China, Japan and Korean. Paeoniflorin is a bioactive monomer extracted from P. lactiflora Pall. with anti-atherosclerosis effects. In this article, we comprehensively reviewed the potential therapeutic effects and molecular mechanism whereby paeoniflorin protects against atherosclerosis from the unique angle of inflammation and immune-related pathway dysfunction in vascular endothelial cells, smooth muscle cells, monocytes, macrophages, platelets and mast cells. Paeoniflorin, with multiple protective effects in atherosclerosis, has the potential to be used as a promising therapeutic agent for the treatment of atherosclerosis and its complications. We conclude with a detailed discussion of the challenges and future perspective of paeoniflorin in translational cardiovascular medicine.

Eukaryotic elongation factor-2 kinase (eEF2K) signaling in tumor and microenvironment as a novel molecular target

Eukaryotic elongation factor-2 kinase (eEF2K), an atypical member of alpha-kinase family, is highly overexpressed in breast, pancreatic, brain, and lung cancers, and associated with poor survival in patients. eEF2K promotes cell proliferation, survival, and aggressive tumor characteristics, leading to tumor growth and progression. While initial studies indicated that eEF2K acts as a negative regulator of protein synthesis by suppressing peptide elongation phase, later studies demonstrated that it has multiple functions and promotes cell cycle, angiogenesis, migration, and invasion as well as induction of epithelial-mesenchymal transition through induction of integrin β1, SRC/FAK, PI3K/AKT, cyclin D1, VEGF, ZEB1, Snail, and MMP-2. Under stress conditions such as hypoxia and metabolic distress, eEF2K is activated by several signaling pathways and slows down protein synthesis and helping cells to save energy and survive. In vivo therapeutic targeting of eEF2K by genetic methods inhibits tumor growth in various tumor models, validating it as a potential molecular target. Recent studies suggest that eEF2K plays a role in tumor microenvironment cells by monocyte chemoattractant protein-1 (MCP-1) and accumulation of tumor-associated macrophages. Due to its clinical significance and the pivotal role in tumorigenesis and progression, eEF2K is considered as an important therapeutic target in solid tumors. However, currently, there is no specific and potent inhibitor for translation into clinical studies. Here, we aim to systematically review current knowledge regarding eEF2K in tumor biology, microenvironment, and development of eEF2K targeted inhibitors and therapeutics.

Levetiracetam inhibits THP-1 monocyte chemotaxis and adhesion via the synaptic vesicle 2A

Long-term therapy with older antiepileptic drugs (AEDs), but not levetiracetam (LEV), may increase the risk of atherosclerosis (AS), suggesting that LEV may have a potential anti-AS effect. The synaptic vesicle 2A (SV2A) is known to the specific binding site of LEV. Numerous studies have documented that SV2A is a membrane protein specifically expressed in nervous system. Interestingly, our previous research showed that SV2A also existed in human CD8+ T lymphocytes. Therefore, we hypothesized that LEV was associated with decreased risk of AS by regulating monocytes chemotaxis and adhesion. We showed that SV2A protein were detected in THP-1 human monocytic leukemia cells. LEV (300 μM) inhibited the chemotaxis and adhesion of THP-1 cells after transfection with plasmids expressing SV2AWT, but not SV2AR383Q which was a known functional mutation site of human SV2A. Furthermore, RT-PCR and western blot analysis demonstrated that LEV (300 μM) decreased the expression level of chemokine-related receptors (CX3CL1, CCR1, CCR2, and CCR5),and reduced levels of phosphorylated AKT (p-AKT) in THP-1 cells with SV2AWT expressing plasmids. Taken together, these findings indicated that LEV has an inhibitory effect on THP-1 monocyte adhesion and chemotaxis, suggesting that SV2A may serve as a novel therapeutic target to prevent AS.

Roles of Reconstituted High-Density Lipoprotein Nanoparticles in Cardiovascular Disease: A New Paradigm for Drug Discovery

Epidemiological results revealed that there is an inverse correlation between high-density lipoprotein (HDL) cholesterol levels and risks of atherosclerotic cardiovascular disease (ASCVD). Mounting evidence supports that HDLs are atheroprotective, therefore, many therapeutic approaches have been developed to increase HDL cholesterol (HDL-C) levels. Nevertheless, HDL-raising therapies, such as cholesteryl ester transfer protein (CETP) inhibitors, failed to ameliorate cardiovascular outcomes in clinical trials, thereby casting doubt on the treatment of cardiovascular disease (CVD) by increasing HDL-C levels. Therefore, HDL-targeted interventional studies were shifted to increasing the number of HDL particles capable of promoting ATP-binding cassette transporter A1 (ABCA1)-mediated cholesterol efflux. One such approach was the development of reconstituted HDL (rHDL) particles that promote ABCA1-mediated cholesterol efflux from lipid-enriched macrophages. Here, we explore the manipulation of rHDL nanoparticles as a strategy for the treatment of CVD. In addition, we discuss technological capabilities and the challenge of relating preclinical in vivo mice research to clinical studies. Finally, by drawing lessons from developing rHDL nanoparticles, we also incorporate the viabilities and advantages of the development of a molecular imaging probe with HDL nanoparticles when applied to ASCVD, as well as gaps in technology and knowledge required for putting the HDL-targeted therapeutics into full gear.

Potential involvement of the 18 kDa translocator protein and reactive oxygen species in apoptosis of THP-1 macrophages induced by sonodynamic therapy

Sonodynamic therapy (SDT) with exogenous protoporphyrin IX (PpIX) or endogenous PpIX derived from 5-aminolevulinic acid (ALA) has been carried out to produce apoptotic effects on macrophages, indicating a potential treatment methodology for atherosclerosis. Our previous studies have found that mitochondria damage by reactive oxygen species (ROS) plays a major role in the SDT-induced apoptosis. This study aimed at investigating the potential involvement of the mitochondrial 18 kDa translocator protein (TSPO) and ROS in the pro-apoptotic effects of SDT on THP-1 macrophages. THP-1 macrophages were divided into control and SDT groups, and went through pretreatment of the specific TSPO ligand PK11195 and ROS scavengers N-Acetyl Cysteine (NAC), then compared with groups without pretreatment. Application of PK11195 reduced intracellular accumulation of endogenous PpIX. PK11195 and NAC reduced the generation of intracellular ROS and oxidation of cardiolipin induced by SDT, respectively. PK11195 and NAC also reduced SDT-induced mitochondrial membrane potential (ΔΨ_m) loss, the translocation of cytochrome c and cell apoptosis. PpIX accumulation, ROS generation and cell apoptosis were also attenuated by siTSPO. Our findings indicate the pivotal role of TSPO and ROS in SDT-induced cardiolipin oxidation, ΔΨ_m collapse, cytochrome c translocation and apoptosis in THP-1 macrophages.